Chapter 2: Erythropoiesis and Anaemia

Question 1

What is the life span of an RBC?

Answer 1

120 days

Question 2

What colour does haemoglobin stain?

Answer 2

pink

Question 3

How does chromatin change as normoblasts develop?

Answer 3

condenses

Question 4

How long does the reticulocyte circulate in the blood until it matures?

Answer 4

1-2days

Question 5

How many mature red cells does on pronormoblast give rise to normally?

Answer 5

16

Question 6

What cells of the kidney produce erythropoietin?

Answer 6

peritubular interstitial cells of the kidney

Question 7

What is the stimulus for erythropoietin production?

Answer 7

oxygen tension in the tissues of the kidney

Question 8

How does erythropoietin stimulate erythropoiesis?

Answer 8

increases number of progenitor cells committed to erythropoiesis by activating transcription factors eg GATA-2 involved in initiating erythroid differetiation in stem cells

Question 9

What occurs with chronic increase in erythropoietin?

Answer 9

extension of eryhtropoiesis into fatty marrow and extramedullary sites

Question 10

How many polypeptide chains does each molecule of haemoglobin have?

Answer 10

4

Question 11

What are the three forms of Hb in adult blood?

Answer 11

HbA ; HbF and HbA2

Question 12

What are the polypeptide chains in HbA?

Answer 12

2x alpha and 2x beta

Question 13

What are the polypeptide chains in HbF?

Answer 13

2x alpha and 2xgamma

Question 14

What are hte polypeptide chains found in HbA2?

Answer 14

2 x alpha and 2xdelta

Question 15

Where does haem synthesis largely take place?

Answer 15

mitochondria

Question 16

What are the main constituents of haem?

Answer 16

protoporphyrin and Fe2+

Question 17

What happens to the haemoglobin moelcule when O2 is unloaded?

Answer 17

the beta chains are pulled apart, allowing 2,3 DPG to bind, resulting in a lower affinity for O2

Question 18

What is methaemoglobinaemia?

Answer 18

circulating Hb has oxidised iron (3+) instead of Fe2+

Question 19

What other name is the anaerobic glycolytic pathway known as?

Answer 19

Embden-Meyerhof pathway

Question 20

What is the function of hte production of NADH in glycolysis?

Answer 20

needed by the enzyme methaemoglobin reductase to change ferric iron to ferrrous form

Question 21

What is the function of the hexose monophosphate shunt?

Answer 21

production of NADPH

Question 22

What is the function of NADPH?

Answer 22

links with glutathione which prevents oxidative stress to RBCs

Question 23

What enzyme is required for the hexose monophosphate shunt?

Answer 23

glucose-6-phosphate dehydrogenase deficiency

Question 24

What is the most abundant protein in the RBC cell membrane?

Answer 24

spectrin

Question 25

What is anaemia defined as?

Answer 25

reduction in haemoglobin concentration of the blood below normal for age and sex

Question 26

What would cause low reticulocyte count in anaemia?

Answer 26

marrow disease; deficiency of iron, B12 or folate; lack of erythropoietin (renal disease); reduced tissue O2 consumption; ineffective erythropoeisis; chronic inflammatory or malignant disease

Question 27

What is seen in the blood if there is ineffective eryhropoiesis?

Answer 27

unconjugated bilirubin and LDH

Question 28

What is macrocytic anaemia?

Answer 28

red cells are abnormally large

Question 29

How are marcocytic anaemias divided?

Answer 29

megaloblastic and non-megaloblastic

Question 30

What is seen in megaloblastic anaemias?

Answer 30

erythroblasts in the bone marrow show delayed maturation of the nucleus compared to the cytoplasm

Question 31

What causes the asynchronous maturation of the nucleus in megaloblastic anaemia?

Answer 31

defective DNA synthesis

Question 32

What is the usual cause of megaloblastic anaemia?

Answer 32

deficiency of vit B12 or folate

Question 33

What is the name of the IF-B12 receptor in the terminal ileum?

Answer 33

cubilin

Question 34

What is B12 mainly bound to in plasma?

Answer 34

haptocorrin

Question 35

Where is haptocorrin synthesised?

Answer 35

granulocytes and macrophages

Question 36

What protein delivers B12 to bone marrow and other tissues?

Answer 36

transcobalamin

Question 37

What is the function of methyl B12?

Answer 37

methionine synthesis: methylation of homocysteine to methionine

Question 38

What is the form of folate which circulates in plasma?

Answer 38

reduced monoglutamate form

Question 39

What is the function of folate?

Answer 39

conversion of uridine to thymidine

Question 40

Where is folate absorbed?

Answer 40

duodenum and jejunum

Question 41

What is the form of folate as a coenzyme?

Answer 41

methyl-THF

Question 42

What drugs inhibit folate reactions?

Answer 42

methotrexate; trimethoprim

Question 43

What is achlorhydria?

Answer 43

absence of HCl

Question 44

What antibodies are invovled in PA?

Answer 44

against gastric H/K ATPase and IF

Question 45

What are the features of vit B12 neuropathy?

Answer 45

progressive symmetrical neuropathy affecting peripheral sensory nerves- mainly DCML; lower limbs more than upper limbs

Question 46

What is the thought to be the cause of neuropathy with vit B12?

Answer 46

defective methylation of myelin

Question 47

What causes the non-megaloblastic macrocytic anaemia?

Answer 47

increased lipid deposition on the red cell membrane or alterations of erythroblast maturation time in marrow

Question 48

What is the most frequent cause of a riased MCV wtihout anaemia

Answer 48

alcohol